SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1544086c6c86bdfe588747fa30ece2c3fc51e2075411b29fbd18946db4ffdb91' 
  AND token = 'eAIuUbxfB/LLJ5W9gnXvD0GyixSmTMfvMhoXvdngUig=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}